Rheological and morphological studies were performed on polymer blends of ethylene-octene copolymer [polyethylene elastomer (PEE)] and polypropylene (PP). The viscosities of PEE, PP, and PEE/PP blends were analyzed using an Instron capillary rheometer and a Rheometrics Dynamic Stress Rheometer, SR 200. A non-Newtonian flow behavior was observed in all samples in the shear rate range from 27 to 2700 s(-1), whereas at shear rates in the range from 0.01 to 0.04 s(-1), a Newtonian flow behavior was verified. The scanning electron micrographs showed that dual-phase continuity may occur between 50 and 60 (wt %) of PEE. This result is consistent with the Sperling＇s model. The mechanical analysis showed that PEE/PP, with 5 wt % of PEE, presented an increase on the mechanical properties and as the PEE content increased, a negative deviation in relation to an empirical equation was observed. Thermal analysis showed that there were no change in the crystallization behavior of the matrix when different elastomer contents were added. Dynamic mechanical thermal analysis showed that samples with low PEE contents presented only one peak, indicating a certain degree of miscibility between the components of these blends. (C) 2000 John Wiley & Sons, Inc.